1. Field of the Invention
The present invention relates to coupling of light into and out of optoelectronic devices (e.g., photonic integrated circuits (PICs)), and more particular to optical connections of optical fibers to optoelectronic devices supported on a circuit board.
2. Description of Related Art
Optoelectronic devices include optical and electronic components that source, detect and/or control light, converting between light signals and electrical signals. For example, a transceiver (Xcvr) is an optoelectronic module comprising both a transmitter (Tx) and a receiver (Rx) which are combined with circuitry within a housing. The transmitter includes a light source (e.g., a VCSEL or DFB laser), and the receiver includes a light sensor (e.g., a photodiode). Heretofore, a transceiver's circuitry is soldered onto a printed circuit board. Such a transceiver generally has a substrate that forms the bottom of a package (either hermetic or non-hermetic), and then optoelectronic devices such as lasers and photodiodes are soldered onto the substrate. Optical fibers are connected to the exterior of the package or fed through the wall of the package using a feedthrough (see, US20130294732A1, which had been commonly assigned to the Assignee/Applicant of the present application, and is fully incorporated as if fully set forth herein).
The cost of the transceiver can be reduced substantially if the package is eliminated, and some commercial transceivers are doing this. For instance, some active optical cable with a silicon photonic integrated circuit (SiPIC) successfully operate without a package. The SiPIC chip is enclosed in epoxy, which is also used to hold an optical fiber array. This approach does not provide a separable connector; the optical fibers are permanently attached to the SiPIC.
US Conec Ltd. introduced the model PRIZM LightTurn connector assembly that is designed as a detachable module-mounted connector. A bottom support is attached to the transceiver, and a connector carrying an optical fiber array is aligned to the support using two pin-in-hole connections. A top clip snaps in place and holds the connector against the support. This connector assembly is fabricated from polymer.
For proper operation, an optoelectronic device supported on a printed circuit board needs to efficiently couple light to an external optical fiber. Most optoelectronic devices (e.g., PICs) require single-mode optical connections that require stringent alignment tolerances between optical fibers and the devices, typically less than 1 micrometer. This is challenging since so many optical fibers are optically aligned to elements on the PICs using an active optical alignment approach in which the position and orientation of the optical fiber(s) is adjusted by machinery until the amount of light transferred between the fiber and PIC is maximized.
The current state of the art is expensive due to the inclusion of a package, excludes the use of common electronics and assembly processes, and/or often not suited to single-mode applications required by many PICs. Active optical alignment involves relatively complex, low throughput undertakings since the laser or photodiode must be energized during the active alignment process. Further, those components that are made of plastic (e.g., the PRIZM LightTurn connector by US Conec Ltd.) are not well suited to single-mode connections, and the plastic components should not be in place during any subsequent soldering processes that may cause the polymer construction to shift and compromise optical alignment.
What is needed is an improved approach to optically couple input/output of optical fibers in optical alignment to optoelectronic components that are supported on a substrate (e.g., a printed circuit board), which improves throughput, tolerance, manufacturability, ease of use, functionality and reliability at reduced costs.